This invention relates to a rotor for a gas turbine with a hub and three dimensionally curved blades which are curved counter to the direction of rotation of the rotor in the radial flow region.
A radial turbine with a rotor comprised of three dimensionally curved blades exhibiting a wing profile and curved counter to the direction of rotation is shown in U.S. Pat. No. 4,243,357 to Flynn et al. The rotor also includes a hub with a disc-shaped terminal region, which the blades touch at their radial flow region.
A gas turbine is also shown in U.S. Pat. No. 4,381,172 to Yu, having three dimensionally curved blades which are curved counter to the direction of rotation in the radial flow region. However, the above references do not disclose equations which describe the curvature of the blades.
It is an object of the present invention, in a radial turbine of the type referred to, to construct the blades so that a gas stream, even a small one, can be passed virtually free from impact, from the pressure side to the suction side of the blades. A further object is to obtain a desired velocity pattern of the gas stream flowing around the blades over each cross-section of the blades by predetermining the curvature of the blades.
These and other objects are achieved according to the invention by providing a rotor of a gas turbine with three dimensionally curved blades which exhibit mean camber lines extending radially from the axis of rotation that are describable by a second order curve equation.
By configuring the blades of a rotor in accordance with the present invention, the gas turbine exhibits improved efficiency in the lower speed range due to the reduction achieved in the angle of impact between the blades and gas stream flow. This produces both a greater unloaded rate of acceleration and also an increase of the effective gas turbine power, whereby greater acceleration power is available for an increase in speed during the running-up phase.